...example 486 328 is divisible by 8 as 328 is divisible by 8 Divisibility Test for 9 A number is divisible by 9 if the sum of its digits is divisible by 9 For example In order to find if 5634 is divisible by 9, add the digits 5 + 6 + 3 + 4 = 18 and 18 is...

...twice the value of the units digit is divisible by 7; - by 8 if the number formed by the last three digits is divisible by 8; — by 9 if the sum of its digits is divisible by 9; - by 10 if it ends in 0; - by 11 if the difference between the cross sums of alternate digits is divisible by...

...debits do not match credits. If the discrepancy is divisible by 9 (recall that a number is divisible by 9 if the sum of its digits is divisible by 9), it is probably a transposition error. This is a rule long observed by all cashiers when they cash out....

...21 and 21 is divisible by 3 so 3684 is divisible by 3 Divisibility Test for 9 A number is divisible by 9 if the sum of its digits is divisible by 9 For example In order to find if 5634 is divisible by 9, add the digits 5 + 6 + 3 + 4 - 18 and 18 is...

...+ab"'2+ /A1) b) Prove: If a = b (mod m), then a" = b" (mod m) Q>. a) Prove that a number is divisible by 9 if the sum of its digits is divisible by 9. b) Use part a) to check whether 4365 is divisible by 9. . a) Simplify 3"(mod 7) for n = 1, 2, 3, 4,...

...1n the next problem, students will discover that, similar to the rule for 3, a number is divisible by 9 if the sum of its digits is divisible by 9. An easy explanation for why this is so is given in the "Digit Problems Revisited" activity in Making...

...• A number is divisible by 3 if the sum of its digits is divisible by 3• A number is divisible by 9 if the sum of its digits is divisible by 9. • A number is divisible by 4 if the number formed by the last two digits is divisible by 4. • A...

...in your proof.] EXERCISE 2B 1 A well-known rule for divisibility is that a number is only divisible by 9 if the sum of its digits is divisible by 9. Consider four-digit numbers of the form 'abcd' which equals 10OOa + lOOb + 10c + d. Show that 'abcd'...

...last two digits are divisible by 4. A number is divisible by 5 if it ends in or A number is divisible by 9 if the sum of its digits is divisible by 9. A number is divisible by 10 if it ends in A number is divisible by 12 if it is divisible by 2 and 6....

...Example Half of 432 = 216. 216 ¡s divisible by 4 so 432 ¡s divisible by 8. A number is divisible by 9 if the sum of its digits is divisible by 9. Example 279 is divisible by 9 since 2 + 7 + 9 = 18 and 18 is divisible by 9. A number is divisible...