Mathnasium #MathTricks: Half Of Odd Numbers (Part 2)

Feb 16, 2022

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.

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 900 + half of 90 + half of 9.

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 450+45+412=49912. We can check that 49912+49912=999.

Now you are ready to find half of any odd number. Click here for more practice problems!

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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