What is the divisibility rule for 400?

Answer 1

A number is a multiple of 400 if the last 4 digits are a multiple of 400

• The 1,000s digit is even and the last 3 digits are 000, 400 or 800
• The 1,000s digit is odd and the last 3 digits are 200 or 600

It also works checking if the number is a multiple of 16 and 25 at the same time because 400 = 2⁴ x 5² = 16 x 25

Answer 2

for any composite number ...

check only the highest power of prime factors divisibility ....

i guess that will do the work

for example ... 400 = 2^4 * 5^2

so you need to check the divisibility by 25 as well as 16

hope this will meet your need