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Hundred Square Grids
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In this video, we will learn how to count onwards in 10s and ones on a hundred square to add two-digit numbers.
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Let’s take a closer look at the numbers on a hundred square grid.
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We can read the numbers from left to right, one, two, three, four, five, six, seven, eight, nine, 10.
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We’re adding one each time.
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And if we count backward, 10, nine, eight, seven, six, five, four, three, two, one, we’re subtracting one each time.
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What happens when we count downwards on a hundred square?
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Five, 15, 25, 35, 45, 55, 65, 75, 85, 95, the numbers are increasing by 10 each time.
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We’re adding 10.
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And if we count upwards, we’re subtracting 10 each time, 99, 89, 79, 69, 59, 49, 39, 29, 19, nine.
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To add four to 46, we need to count forward, one, two, three, four.
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46 add four equals 50.
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What happens if we want to add a multiple of 10 to a number?
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How would we add 50 to 33?
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We know that 50 has five 10s.
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And to add 10, we need to count downwards, 10, 20, 30, 40, 50.
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33 add 50 equals 83.
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To add 10, we counted downwards on the hundred square.
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50 is five 10s, so we counted downward five squares.
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Find the sum of 33 and eight.
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Use the hundred square to help you.
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We need to start at number 33 on the hundred square.
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And we need to add eight, which means we need to count forward eight, one, two, three, four, five, six, seven, eight.
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The sum of 31 [33] and eight is 41.
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We started at 33 on the hundred square and we counted forward eight squares.
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Let’s practice one more example of adding using a hundred square.
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50 people are going to a party.
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Then, 15 more people decide to go.
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How many people are going to the party?
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Find the number by using the chart to count.
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We know that 50 people are going to a party.
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Then, 15 more people decide to go.
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So, we need to start counting at 50 on a hundred square and count forward 15 squares.
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15 is made from a 10 and a five.
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We can quickly add 10 to 50 by counting down one square on the hundred square.
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We know that 50 plus 10 is 60.
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Now we just need to add the five from 15.
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If we start at 60 and count forward five spaces, or five squares, we land on 65.
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50 plus 15 equals 65.
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To add 15 to 50, we counted down one square to add 10 and across five to add five.
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50 plus 15 equals 65.
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In this video we’ve learned how to count forward in 10s and ones on a hundred square to add two-digit numbers.