How do you set the date and time?

You can't, it's a 'feature', set for every 7 minutes of inactivity. However.....

I don't think you can turn off sleep mode. However, after the calculator goes into sleep mode, to return to where you are working just press the C/CE key (red key bottom left). The calculator will return to where you left off.

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I hate Canon's automatic shut off feature in some of its models. Answer: Hi! The Canon MP27DII calculator will go to sleep after approximately 7 minutes ...

How To Turn Off Sleep Mode ' Canon MP25DV Support

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Oct 11, 2018 - Canon MP25DV - would like to turn off the automatic sleep mode af. ... The machine is design with energy saving mode, Press <Power button >. ... and easy-to-use keys that automatically perform complicated applications, ...

SOLVED: CANON MP25DV TURNS OFF EVERY 7 MINUTES ...

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Aug 10, 2018 - CANON MP25DV TURNS OFF EVERY 7 MINUTES. HOW TO STOP THIS? - Office Equipment & Supplies.

Hello , Please check below manual for more details. https://www.usa.canon.com/internet/portal/us/home/support/details/calculators/printing-calculators/mp25dv?tab=manuals
Thanks.

There is a setting for darkness. Check it out in the manual or directions.

Top right column on page 3: http://www.manualslib.com/manual/355936/Canon-Mp25dv.html

How to Set the Time & Date for a MP25DV Canon Calendar & Clock Printing Calculator

The steps listed in the Calculator Instruction Manual for the Canon MP25DV Calculator did not work.
The correct steps for setting the time and date on this calculator are listed below:

1. Press the time/calendar button one to select the date mode. The display should show the month-day-year.
2. Hold down the = button until the month start flashing.
3. Use the number keys to enter the current date, month and year. Example 07-22-2021
4. Press the = key to set the current date.
5. Press the CE/C key to return back to the calculator mode.
6. Press the time/calendar button twice to select the time mode. The display show the
hour-minute-seconds & time of day. Example 02-01-14 A
7. Hold down the = button until the hour start flashing.
8. Use the number keys to enter the current time.
9. Press the X button for (A) a.m. or (P) for p.m.
10. Press the = key to set the current time.
11. Press the CE/C key to return back to the calculator mode.
12. To check the current date and time on your calculator, press the calendar/time button once
for date and twice for time.

To set date:
1. Press the calendar/clock button (display should show date)
2. Press and hold the 'time set' button for 3 seconds (first digit of the date should flash)
3. Use the numeric keys to enter date using mmddyyyy format
4. Press 'time set' button

To set time:
1. Press the calendar/clock button twice (display should show time)
2. Press and hold the 'time set' button for 3 seconds (first digit of the time should flash)
3. Use the numeric keys to enter time using hhmm format, press 'AM/PM' button as needed
4. Press 'time set' button

The '12/24' button changes between 12 hour and 24 hour format for time.
The 'format' button changes the date format from mmddyyyy to ddmmyyyy or yyyymmdd.

press clock/calendar once to set date
1) press equal numbers will flash then use number keys to current time then the X to set am and pm. press = again to set time
2)press clock/calendar until date flashes. use number keys to current date. Press = to set

the rate button is the 2nd slide switch from the right.. just above the GT key.

The trick is to hold down the time set button (=) until the time flashes and once the new info is entered, press time set and it will stay.  same with the date.  You kinda need to play around with it.  Thats how i learned.   

on the bottom of your calculator is a reset button, with a paperclip or a pen press that button. Then, press the calendar, clock key. next, press the equal sign key until the date is flashing type in the date using 11172006. press the equal sign again and the date is set. Next press the calendar, clock key again the time should show up (12-00-00)press the equal sign again until the time starts to flash. enter in the time using 0903 (9:03) press the equal sign again. Time is set. to display the date and time when not using the calculator, press the calculator, clock key 2x's. to go to compute mode press the red CE/C button.