Free interactive math game: Divisibility by 5 — Pick the divisible number. Part of the Divisibility & Numbers category on MathKite.
Taken from the generator that powers this exercise. A fresh set appears every time the page is opened, and the printable worksheet holds ten of them.
Spotting which number divides evenly without doing the division.
Each divisor has its own test: 2 needs an even last digit, 5 needs a last digit of 0 or 5, 10 needs a final zero, 3 and 9 need their digit sum to be divisible by 3 or 9, and 4 needs the last two digits to be.
135 has digits summing to 9, so it is divisible by both 3 and 9.
Applying the digit-sum test to 2 or 5. Those depend only on the final digit, never on the sum.