Math Facts

Mental math tricks for the CLT and SAT

The CLT math section is taken without a calculator, and even on the Digital SAT (which has a calculator built in) quick mental math saves minutes. These are the moves worth knowing cold.

Updated October 29, 2026

Tricks worth knowing

  • Times 5: times 10, then halve. 5 × 48 = 480 ÷ 2 = 240.
  • Times 25: times 100, then divide by 4. 25 × 36 = 3,600 ÷ 4 = 900.
  • Times 11 (two digits): add the digits and put the sum in the middle. 11 × 43: 4, 4 + 3, 3 = 473. If the sum is 10 or more, carry: 11 × 78 = 858.
  • Percents flip: 8% of 50 is the same as 50% of 8, which is 4.
  • Squares near 50: 48² = (50 − 2)² = 2,500 − 200 + 4 = 2,304.
  • Difference of squares: 31 × 29 = (30 + 1)(30 − 1) = 900 − 1 = 899.
  • Split and add: 7 × 36 = 7 × 30 + 7 × 6 = 210 + 42 = 252.

Fractions to know as decimals and percents

  • 1/2 = 0.5 = 50%
  • 1/3 ≈ 0.333 = 33⅓%
  • 1/4 = 0.25 = 25%
  • 1/5 = 0.2 = 20%
  • 1/6 ≈ 0.167
  • 1/8 = 0.125 = 12.5%
  • 3/8 = 0.375
  • 5/8 = 0.625
  • 1/9 ≈ 0.111
  • 1/12 ≈ 0.083

Practice it

Math Facts has tracks for exactly this: mental math, fractions and percents, squares and roots, and mixed no-calculator test questions, in 60-second sprints.

Practice mental math freeTry CLT math practice

Questions people ask

Can you use a calculator on the CLT?

No. The CLT does not allow calculators, so every math question is built to be solved by hand. Fast arithmetic and fraction sense matter more than on most tests.

Does the Digital SAT allow a calculator?

Yes. The Digital SAT allows a calculator on the whole math section and has a graphing calculator built into the testing app. Mental math still saves time on the many questions where typing would be slower.

Sources

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