11
(9, 18, 27, 36, 45, 54, 63, 72, 81, 90 and 99)
Those numbers divisible by 9 are the multiple of 9; thus need to know how many multiples of 9 there are between 1 and 100:

100 ÷ 9 = 11 r 1 ÷ last multiple of 9 is 11 × 9 (= 99)
→ There are 11 - 1 + 1 = 11 numbers between 1 and 100 which are divisible by 9.

(They are 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99.)

7 0

3 years ago

Prove that equation ax^2+2hxy+by^2 always represent a pair of straight lines passing through the origin

GarryVolchara [31]

You should try a calculator 2 6

4 0

2 years ago