# Hairu and the numbers part 20 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings on Solving Singapore Primary School Mathematics. The blog presenting the Math Concept, Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids can learn the skills of dealing with Math Question Solving, Math Modeling and Problem Sums from Lower Primary School to Upper Primary School level after reading the blog postings. This posting is an upper primary school math question on Number and Problem Sum.

To read the posting on Hairu and the numbers to understand the concept of number.

Challenge yourself with the question before look for the given solution‼!

Upper primary school mathematics question UPQ324

The sum of three numbers is 78. The first number is 7 more than the second number. The third number is 4 less than the second number. Find the third number.

Solution:

Draw the model

To base 3rd number as 1 unit

From the model

3 units = 78 – 4 – 4 – 7 = 63

1 unit = 63 ÷ 3 = 21

The 3rd number is 21