Question

Find the sum of the numbers between 300 and 400 that leave no remainder when divided by 6, 9 or 12.

Answer 1

so whats the first number thats divisible by 6,9, and 12 ?

Answer 2

heard of LCM before ?

Answer 3

36

Answer 4

yes ! so the least positive number thats divisible by 6, 9, and 12 is 36

Answer 5

360

Answer 6

and all other numbers that are divisible by 6,9, and 12 will be of form : `36k`

Answer 7

thats a good observation !
yes 360 is of form 36k

Answer 8

324,360,396,432,

Answer 9

subtract 36 from 360, you will get another number of form 36k

Answer 10

360-36 = 324

Answer 11

adding 36 will give you another number :

360+36 = 396

Answer 12

so the required numbers are : 324, 360, 396