Facilitator’s Guide G04 ~ Mathematics
Unit
1
Attempt 2: To choose 6 as the answer will make the number sentence FALSE. Guess another answer. Since 6 is not enough to subtract from 156 to get 149, you must choose a greater number. Use the number 7.
156 – 7 = 149
Using this method, it may take a number of tries to solve the number sentence. It is time-consuming and not always the best method to use.
ACTIVITY 8 1.
Solve the number sentences using the trial and improvement method. 1.1 1.2 1.3 1.4 1.5
Question
Answer
458 – = 453
5
29 + = 143
114
15 + = 105
90
6
985 + = 991
110
326 – = 216
Checking the solution by substitution is very similar to the trial and improvement method. You have to study the number sentence and then decide on an answer. You then replace the answer in the number sentence and do the calculation. The number sentence must be TRUE. Number sentences are also a way of showing equivalence. What does equivalence mean? Equivalence is when one side of the number sentence is equal to the other side of the number sentence. In other words, showing that the number sentence is true.
The left side of the number sentence is equivalent (equal to) the right side of the number sentence. It means that the number sentence is true. Number sentences may also be used in flow charts and tables. Look at a few examples.
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