Numbers too big to compute, step by step
Multiply a hundred sevens together.
The question
What day of the week will that be?
Only the leftover moves the day
from:Monday· days:135
MoTuWeThFrSaSu
19×7=133
135−133=2
Monday+2=Wednesday
- Two things are given and one of them is far too big to count through: today is Monday, and the wait is 135 days.
- Counting 135 days one at a time is not a method, so use the thing days of the week do: they come back round every 7. A whole week later is the same day you started on, and that is true of any number of whole weeks.
- So take the whole weeks out and they change nothing. 19 weeks is 19 × 7 = 133 days, and 135 − 133 = 2 days are left over. Only those 2 move the day at all.
- Now count 2 on from Monday — and count the day AFTER today as one, because today is where you are, not a day of waiting. That lands on Wednesday.
How it works.
- 01
Two things are given and one of them is far too big to count through: today is Monday, and the wait is 135 days.
- 02
Counting 135 days one at a time is not a method, so use the thing days of the week do: they come back round every 7. A whole week later is the same day you started on, and that is true of any number of whole weeks.
- 03
So take the whole weeks out and they change nothing. 19 weeks is 19 × 7 = 133 days, and 135 − 133 = 2 days are left over. Only those 2 move the day at all.
- 04
Now count 2 on from Monday — and count the day AFTER today as one, because today is where you are, not a day of waiting. That lands on Wednesday.