'Subtraction book numeracy resources' diaporamas de présentation

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Equal Additions

Equal Additions. I am learning to solve subtraction problems by equal additions that turn one of the numbers into a tidy number. Numbers like 10, 20, 30, 40 etc. Alice has $304 and spends $198. How much money does she have left?. $304 - $198.

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Near Doubles

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Three or more at a time.

Three or more at a time. I am learning to look at the addition and subtraction of three or more numbers to calculate easy combinations first. e.g. 3 + 6 + 7 = ?. 3 + 7 = 10. 10 + 6 = 16. Angela has $82, Sam has $114 and Julie has $18. How much do they have in total?. 82 + 114 + 18 = ?.

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Estimation as a check

Estimation as a check. I am learning to check any addition and subtraction problem I cannot solve mentally by estimating the answer. You may have used a calculator or an algorithm. Alex had $479 and he spent $138. How much money does he have left?. 479 - 138 = ?.

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Decomposition

Decomposition. I am learning a standard method of doing a subtraction problem on paper when the numbers are too difficult to find the answer mentally. Numbers are set out directly below each other. e.g. 243. In your head. - 165.

217 views • 4 slides