10000 x 365 = 3650000
10000 times 365 is 3650000. It is the yearly total of anything done ten thousand times a day, most often steps: hitting 10000 steps every day for a year comes to 3650000 steps.
10,000 × 365 = 3,650,000
Adding 10,000 to itself 365 times gives the same answer.
The working
Multiplying by 10000 appends four zeros, so 365 becomes 3650000 and nothing else has to happen. Spoken aloud that is three million six hundred fifty thousand, or 3.65 million if you prefer the shorter form.
Leap years change it
A leap year has 366 days, which adds one more 10000 and gives 3660000. Across a four-year span containing one leap year there are 1461 days, so the honest total is 14610000, not the 14600000 you get from multiplying 3650000 by four. The gap is a full day’s worth.
The rest of the ladder
Hold 365 steady and change the daily figure. 100 x 365 is 36500 and 1000 x 365 is 365000. Each rung multiplies by ten, so all three answers are the same leading digits with more zeros behind them.
Weeks instead of days
If the count is weekly rather than daily, the multiplier is 52, not 365 — see 1000 x 52. Using 365 on a weekly figure overstates the year by about seven times, since 365 divided by 52 is just over 7.