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Brainteasers

Puzzles to test mathematical skills, set by Anita Straker. Solutions below More brainteasers on www.tes.co.ukteacherbrainteasers

AGES 7-11

572 is a three-digit number.

pt = 572 The sum of the digits is 5+ 7 + 2 = 12.

What is the smallest three-digit number you can find with a digit sum of 23?

How many three-digit numbers can you find altogether with a digit sum of 23?

AGES 8-12

AT THE ICE RINK

It is a Tuesday. Zoe, Holly and Ram are skating at the ice rink.

The ice rink opens every day of the week.

Zoe goes skating every third day. Holly goes skating every fourth day. Ram goes skating every fifth day.

What day of the week will it be when they are all together at the ice rink again?

SOLUTIONS Three-digit numbers The smallest three-digit number with a digit sum of 23 is 599. There are 15 different possibilities altogether: three arrangements of 995 (995, 959, 599); six arrangements of 986 (986, 968, 896, 869, 698, 689); three arrangements of 977 (977, 797, 779); three arrangements of 887 (887, 878, 788)

At the ice rink It will be a Saturday. The first number that is an exact multiple of 3, 4 and 5 is 60. 60 days is 8 weeks and 4 days, and counting on 4 days from Tuesday takes us to Saturday.

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