-1

How to find numbers divisible by 3 between 200 and 400 without testing every number in the range? And explain the solution to a 10 year old!

user3919652
  • 17
  • 2
  • What do you mean? Do you want a list of the multiples of 3? Do you want to know how many there are? – saulspatz Apr 02 '18 at 05:11
  • Hint: exactly one of three consecutive numbers is a multiple of $3$. – dxiv Apr 02 '18 at 05:11
  • Well, are the numbers divisible by $3$ just randomly distributed that if you find one you'd have no idea when or if you'd find the next one? Or are the numbers that are divisible by $3$ pretty predictable and distributed with some order? – fleablood Apr 02 '18 at 05:13

1 Answers1

0

a) Find the first one. $200/3 = 66 \text{ r } 2$, so the first one is $201 = 67\times 3$.

b) Find the last one. $400/3 = 133 \text{ r } 1$, so the last one is $399 = 133\times 3$.

c) Find how many integers are in the range $[67..133]$ inclusive.

Joffan
  • 39,627