I have a timex chrono calculator watch that is

https://www.timex.com/watch-manuals.html

I didn't see it there, but they usually provide contact information to request assistance.

https://www.amazon.com/Marathon-Timex-T5K360-Digital-Mid-Size/dp/B00284C9SM

Amazon vendors often answer customer questions on their web site.

Examples:
Question:
does this watch count distance?
Answer:
No, this watch does not count distance. It has two time zone settings and a stop watch.
By Mindyx on June 24, 2017 See more answers (4)
Question:
Does this watch show seconds as well?
Answer:
Yes.
By Mom of three on July 22, 2017 Yes the seconds show on the face along with the time.
By Pati D on July 21, 2017Collapse all answers
Question:
What is the length of the watch band - I need at least 8" in length
Answer:
6 inch
By PromenadeWatches SELLER on August 4, 2017 Tip to tip (including buckle) is 9 inches. 8 inches without the buckle
By Brittney on August 1, 2017
Hello, standard wrist size for a women's watch fits a maximum of 7.5 inches.
By Timex Customer Service MANUFACTURER on August 3, 2017

Collapse all answer
Question:
IS this a chrono watch?
Answer:
Hello, thank you for your question. Yes this watch has the chronograph feature.
By Timex Customer Service MANUFACTURER on August 29, 2017 No, it is not a chrono watch, but it has a 24-hour stop watch.
By Mindyx on August 28, 2017Collapse all answers
Question:
Does this watch have presets for the countdown timer? For example 30 secs, 1 min, 3 min, 5 min, 15 min, 30 min, 45 min, 1 hour? Thank you!
Answer:
No
By Mom of three on February 16, 2018 Hello, thank you for your question! This watch doesn't have timer feature.
By Timex Customer Service MANUFACTURER on February 20, 2018
Collapse all answers

Question:
Does this watch have a countdown timer?
Answer:
Yes, this watch has a 24 hour countdown timer.
By Timex Customer Service MANUFACTURER on March 13, 2017 No. But the size of the numbers and night light button are great features. Has count UP timer.
By Mom of three on March 13, 2017

Collapse all answers

Question:
How do I change the time showing back to international (military) time?
Answer:
By pressing the lower left hand button to scroll through he screens, go to where it displays the time with the date up above. Press the upper left hand corner button once.
By Mom of three on August 16, 2017 Hello, thank you for your message. Here are the instructions in setting the time including the time format.

To set time and date: ... see more
By Timex Customer Service MANUFACTURER on August 15, 2017Collapse all answers

From the time mode, just press mode button once and the word "chrono" will appear.

Welcome to FixYa!
Here's your request.
TIME AND DATE 1. Press and hold MODE until HOURS digits flash (you'll be in Alarm Mode) Press MODE again to enter TIME mode, SECONDS digits will flash. 2. Press ADJUST to set SECONDS to zero. 3. Press START/STOP to select MINUTES. 4. Press ADJUST to change. 5. Repeat to set HOURS, MONTH, DAYS, and DAY of WEEK. Go through 12 hours to set AM or PM. 6. Press MODE when done. 7. To display DATE from Time display , press START/STOP. 8. With DATE displayed press and hold START/STOP, then press ADJUST to change display between DATE-MONTH and MONTH-DATE. 9. With TIME displayed, press and hold ADJUST, then press MODE to switch between 12-and 24-hour format.
ALARM AND HOURLY CHIME 1. Press and hold MODE until HOURS digits, DAY, and A or P (for AM or PM) flash. 2. Press ADJUST to change HOURS digits. Go through 12 hours for AM or PM. 3. Press START/STOP to select MINUTES. 4. Press ADJUST to change.. Press MODE when done. 5. Press and hold ADJUST, then press START/STOP to turn chime on/off. Press START/STOP again to turn alarm on /off. Release START/STOP when done.
CHRONOGRAPH 1. Chronograph will count up to 24 hours. Lap times are not stored. After 40 minutes chrono display changes from seconds to minutes. 2. With time displayed, press MODE to select Chrono Mode. 3. Press START/STOP to start. 4. Press ADJUST to view lap time. Press again to sesume lap timing. 5. Press START/STOP to stop timing . Press ADJUST to reset chrono to zero. 6. Repeat for successive laps.
Thank you for using FixYa! Have a great day.
Jas247

Many Iroman (men) manuals here

http://www.timex.com/info/Product_Instruction_Guides_Downloads

Click on my profile (escapement), then click on Tips and Tricks. There you will find link to all TIMEX watch manuals.

Setting Time after setting it, shows other type of settings 24/12 hrs, beep, chime and it shows Chrono where you can display or not. :)

TIME AND DATE
1. Press and hold MODE until HOURS digits flash (you'll be in Alarm Mode) Press MODE again to enter TIME mode, SECONDS digits will flash.
2. Press ADJUST to set SECONDS to zero.
3. Press START/STOP to select MINUTES.
4. Press ADJUST to change.
5. Repeat to set HOURS, MONTH, DAYS, and DAY of WEEK. Go through 12 hours to set AM or PM.
6. Press MODE when done.
7. To display DATE from Time display , press START/STOP.
8. With DATE displayed press and hold START/STOP, then press ADJUST to change display between DATE-MONTH and MONTH-DATE.
9. With TIME displayed, press and hold ADJUST, then press MODE to switch between 12-and 24-hour format.

ALARM AND HOURLY CHIME
1. Press and hold MODE until HOURS digits, DAY, and A or P (for AM or PM) flash.
2. Press ADJUST to change HOURS digits. Go through 12 hours for AM or PM.
3. Press START/STOP to select MINUTES.
4. Press ADJUST to change.. Press MODE when done.
5. Press and hold ADJUST, then press START/STOP to turn chime on/off. Press START/STOP again to turn alarm on /off. Release START/STOP when done.

CHRONOGRAPH
1. Chronograph will count up to 24 hours. Lap times are not stored. After 40 minutes chrono display changes from seconds to minutes.
2. With time displayed, press MODE to select Chrono Mode.
3. Press START/STOP to start.
4. Press ADJUST to view lap time. Press again to sesume lap timing.
5. Press START/STOP to stop timing . Press ADJUST to reset chrono to zero.
6. Repeat for successive laps.

ANALOG TIME
Pull CROWN and turn to set HOUR and MINUTE hands. TIME AND DATE A. Press and hold SET. SECONDS digits will flash. B. Press SPLIT/RESET to set SECONDS to zero. C. Press MODE to select HOURS. D. Press SPLIT/RESET to advance hours digits. Go through 12 hours for AM or PM. E. Press MODE to select MINUTES, press SPLIT/RESET to advance. F. Repeat to set MONTH, DATE, DAY, 12- or 24-hour time display. G. Press SET when done. BASIC OPERATIONS Press MODE to cycle through CHRONO, TIMER, and ALARM modes. Press INDIGLO to illuminate watch face. In any mode, press MODE to view time display. Press any button to stop alarm or timer beeps. INDIGLO INDIGLO CHRONOGRAPH A. Press MODE until CHRONO appears. B. Press START/STOP to start. C. Press SPLIT/RESET to record lap time. Display pauses. D. Press MODE to resume display of lap and split time (automatic after 10 seconds). E. Press START/STOP to pause chrono. F. Press START/STOP to resume. G. Press START/STOP to stop. H. When timing is stopped, press SPLIT/RESET repeatedly to recall last eight lap and split times. I. Press and hold SPLIT/RESET to reset chrono. MODE MODE START/ STOP START/ STOP SPLIT/ RESET SPLIT/ RESET SET SET CROWN COUNTDOWN TIMER A. Press MODE until TIMER appears. B. Press SPLIT/RESET to select timer operation (Countdown and Stop; Countdown and Repeat; Countdown and Start chrono). C. Press SET. HOURS digits will flash. Press SPLIT/RESET to advance digits. D. Press MODE to select TENS of MINUTES. Press SPLIT/RESET to advance. E. Repeat to set MINUTES, TENS of SECONDS, and SECONDS. F. Press SET when done. G. Press START/STOP to start timer. H. Press START/STOP to pause, press again to resume. I. When timer is stopped, press SPLIT/RESET to reset timer. Watch will beep when countdown reaches zero. ALARM AND CHIME A. Press MODE until ALARM appears. B. Press SET to select HOURS. Digits will flash. C. Press SPLIT/RESET to advance digits. Go through 12 hours for AM or PM. D. Press MODE to select TENS of MINUTES. E. Press SPLIT/RESET to advance. Repeat for MINUTES. F. Press SET when done. G. Press START/STOP to turn alarm on or off. H. Press SPLIT/RESET to turn chime on or off. When alarm time is reached, watch will beep for 20 seconds, or until any button is pushed. Alarm will repeat every 24 hours until deactivated. INDIGLO® NIGHT-LIGHT WITH NIGHT-MODE® FEATURE A. Press INDIGLO to activate light. Patented (U.S. Patent Numbers 4,527,096 and 4,775,964) electroluminescent technology used in the INDIGLO® night-light illuminates watch face at night and in low light conditions. B. Press and hold INDIGLO for three seconds (beep will sound) to activate or de-activate NIGHT-MODE® feature. C. While in NIGHT-MODE® feature, press any button to illuminate watch face for 3 seconds. Chime on Alarm on If your watch is water-resistant, meter marking or ( ) is indicated. Water-Resistance Depth p.s.i.a.* Water Pressure Below Surface 30m/98ft 60 50m/164ft 86 100m/328ft 160 *pounds per square inch absolute WATER AND SHOCK RESISTANCE WARNING: TO MAINTAIN WATER-RESISTANCE, DO NOT PRESS ANY BUTTONS UNDER WATER. 1. Watch is water-resistant only as long as lens, push buttons and case remain intact. 2. Watch is not a diver watch and should not be used for diving. 3. Rinse watch with fresh water after exposure to salt water. 4. Shock resistance will be indicated on the watch face or caseback. Watches are designed to pass ISO test for shock resistance. However, care whould be taken to avoid damaging crystal.

These are settings for the Timex SPORTS 1440 Magnetism (5b841 -W163US)
These are for the 4 button SPORTS 1440 (not 6 button) - they will also work for the 1440 SPORTS "Informer" model wrist watch - you will NOT find these instructions on the Timex website - only the 6 button which will not work on these watches is on that site!

TIME AND DATE

1. Press and hold MODE until HOURS digits flash (you'll be in Alarm Mode) Press MODE again to enter TIME mode, SECONDS digits will flash.
2. Press ADJUST to set SECONDS to zero.
3. Press START/STOP to select MINUTES.
4. Press ADJUST to change.
5. Repeat to set HOURS, MONTH, DAYS, and DAY of WEEK. Go through 12 hours to set AM or PM.
6. Press MODE when done.
7. To display DATE from Time display , press START/STOP.
8. With DATE displayed press and hold START/STOP, then press ADJUST to change display between DATE-MONTH and MONTH-DATE.
9. With TIME displayed, press and hold ADJUST, then press MODE to switch between 12-and 24-hour format.

ALARM AND HOURLY CHIME

1. Press and hold MODE until HOURS digits, DAY, and A or P (for AM or PM) flash.
2. Press ADJUST to change HOURS digits. Go through 12 hours for AM or PM.
3. Press START/STOP to select MINUTES.
4. Press ADJUST to change.. Press MODE when done.
5. Press and hold ADJUST, then press START/STOP to turn chime on/off. Press START/STOP again to turn alarm on /off. Release START/STOP when done.

CHRONOGRAPH

1. Chronograph will count up to 24 hours. Lap times are not stored. After 40 minutes chrono display changes from seconds to minutes.
2. With time displayed, press MODE to select Chrono Mode.
3. Press START/STOP to start.
4. Press ADJUST to view lap time. Press again to sesume lap timing.
5. Press START/STOP to stop timing . Press ADJUST to reset chrono to zero.
6. Repeat for successive laps.

Have fun! - Not a bad watch for the money! - - Silver Bullet