Here is a number sense trick to subtract without borrowing.

Let’s say we want to subtract 54 from 900. Since the values of the digits in the *ones* and *tens* places of 900 are both less than the values of the same digits of 54, we need to borrow to find the difference.

With this Mathnasium #MathTrick, we can avoid borrowing by moving the “difference window” to find an easier difference. We can change 900 to 899 by subtracting 1 and accounting for the same change in 54. Subtracting 1 from 54, we have 53.

Now, the values of the digits in the *ones *and *tens* places of 899 are both larger than the values of the same digits of 53. Using mental math, the difference of 899 – 53 is **846**, and so

900 – 54 = **846**.

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