# Number Sense Blog ### Mathnasium #MathTricks: Number Sense (Subtraction)

Oct 18, 2021

Here is a number sense trick to help you calculate subtraction using mental math.   We want to find the difference of 100 – 76. Using our number sense, we turn to “friendly numbers” to calculate how far apart are 76 and 100.   Starting... ### Mathnasium #MathTricks: Number Sense (Addition)

Oct 13, 2021

Here is a number sense trick to help you calculate addition using mental math.   We want to find the sum of 9 + 8 + 7. Using our number sense, we turn to “friendly numbers” such as 10 or multiples of 10, to help make this math easier to work... ### Mathnasium #MathTricks: Quarter Of Numbers

Oct 11, 2021

The word quarter means “4 parts the same,” “four equal parts”.   To find a quarter of any amount, cut the whole into “4 parts the same” and take any one part. The trick to doing this easily is to “cut it in half and then cut the half in half... ### Mathnasium #MathTricks: Half of Odd Numbers

Oct 8, 2021

Recall that half means “2 parts the same,” “two equal parts.”   Half of 6 circles is 3 because we cut the whole into “2 parts the same” and take one part.   To find half of 7, we bring in one more circle and cut our new whole into “2 p... ### Mathnasium #MathTricks: Half of Even Numbers

Oct 6, 2021

The word half should bring to mind the image of two equal parts: “2 parts the same.”   To find half of any amount, cut the whole into “2 parts the same” and take either one. To find half of 6, we cut the whole of 6 circles into “2 parts t...

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