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Problem #59 · September 24, 2026

Order of operations

Find the value of the expression. 10⋅9−9⋅8+8⋅7−7⋅610 \cdot 9 - 9 \cdot 8 + 8 \cdot 7 - 7 \cdot 6
  1. A3232
  2. B1616
  3. C4848
  4. D3030

WORKED EXAMPLE

Solution

We calculate each product: 90−72+56−4290-72+56-42. From left to right: 90−72=1890-72=18, 18+56=7418+56=74, 74−42=3274-42=32. Grouping is also possible: 9⋅(10−8)+7⋅(8−6)=18+14=329\cdot(10-8)+7\cdot(8-6)=18+14=32.
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