December 8

Maths Mate Sheet 7 Question 23 (Term 4 2014)

Prediction: I predict this question  will be about addition because of the repeated pluses in the question.

Read: The digit sum for 95 is 9 + 5, or 14. How many two digit numbers have the digit sum of 9.

Clarification: None needed.

The Big Question: How many two digit numbers have the digit sum of 9.

Mathematician’s Toolbox: Have I seen a similar problem?

Solving: Firstly I know that all the nine times tables with two digit numbers add up to nine so I did: 2×9,3×9,4×9,5×9,6×9,7×9,8×9, 9×9 and 10×9. Thats 9 sums so the answer is 9.

Conclusion: So the answer was 9.


Posted December 8, 2014 by Rat in category maths, Other, Uncategorized

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