Video: Evaluating and Comparing Division Expressions with Addition Expressions

Use <, =, or > to fill in the blank: 142 ÷ 2 _ 80 + 9.

03:31

Video Transcript

Use the symbol for is less than, is equal to, or is greater than to fill in the blank. 142 divided by two what 80 plus nine.

In this problem, we’ve got two expressions that we need to compare. Firstly, we have a division, 142 divided by two, in other words, half of 142. And then, we also have an addition, 80 plus nine. And in-between the expressions, we have a blank that we need to fill in by using a symbol, a symbol that can compare the two expressions together. And the three symbols that we have to choose from are is less than, is the same as, or is equal to, and finally is greater than.

Now, comparing two numbers is fairly straightforward. We just need to look at the numbers and think about what they’re worth. But how can we compare a division and an addition like this? Well, we need to work out the division and work out the addition. That way we can see what they’re worth, and then we can compare their values. Perhaps the easier of the two expressions to work out first is the addition, 80 plus nine. 80 is another way of saying eight tens. And nine is another way of saying nine ones. And if we add eight 10s and nine ones together, we get 89.

So, now we know one of the values that we’re comparing to. Is the first expression less than 89, equal to 89, or greater than 89? To find the answer, we need to divide 142 by two. There are lots of ways we could do this, but one way is to partition 142 into 140 and two. We know half of 14 is seven. So, half of 14 tens, or 140, is seven tens, or 70. And, of course, half of two is one. And if we combine our two parts back together, we get the answer to 142 divided by two. 70 plus one is 71. So, half of 142 is 71.

Now, when we compare two values we always read across from left to right, so we need to look at the number 71 first. Is 71 less than 89, equal to 89, or greater than 89? Well, 71 has seven tens, but 89 has eight tens, so we know 71 is less than 89. And so, the symbol we need to use in-between the expressions to fill in the blank is less than.

We found the answer by calculating 142 divided by two and also working out what 80 plus nine was worth. The two numbers were 71 and 89. And because 71 is less than 89, we can say that 142 divided by two, is less than 80 plus nine. The correct symbol to fill in the blank is the one that represents is less than.

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