Welcome to Mathnasium’s Math Tricks series. Our previous Math Tricks have looked at strategies for finding half of odd numbers whose tens digits are even. Today we are focusing on a strategy to find the half of any odd number, such as 99.
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To find half of 999, we decompose the whole into its parts and find half of each part. Remember that to find half of nine hundred ninety-nine means to find “Two parts the same,” “Halfway between,” or, “What number plus itself is equal to nine hundred ninety-nine?”.
Step 1: Nine hundred ninety-nine decomposed is nine hundreds, nine tens, and nine ones.
Step 2: Half of nine hundred ninety-nine is equal to half of
Step 3: From our Math Trick we know half of nine is four-and-a-half, and half of ninety is forty-five (not forty-and-a-half).
Step 4: Since we know half of nine is four-and-a-half, we automatically know that half of nine hundred (or nine hundreds), is four-and-a-half hundreds. So, half of nine hundred is four hundred fifty.
Step 5: Finally, half of nine hundred ninety-nine is equal to
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Now you are ready to find half of any odd number. Click here for more practice problems!
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If you missed our Math Tricks video on the Half of Odd Numbers (Part 2), check it out on our social media channels. Until next time!
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