Top 10 Math Shortcuts
Your quick-reference cheat sheet for mastering high school math faster. Perfect for tests, homework, and boosting your confidence.
1. The 11 Multiplication Trick
To multiply any two-digit number by 11, add the two digits and place the sum in the middle.
11 × 43 ➔ 4 + 3 = 7 ➔ Result: 4732. Difference of Squares
Whenever you see a² - b², you can instantly factor it into (a - b)(a + b).
x² - 25 ➔ (x - 5)(x + 5)3. Pythagorean Triples
Memorize 3-4-5 and 5-12-13. If you see these ratios on a right triangle, skip the calculation!
A triangle with legs 6 and 8 has a hypotenuse of 10 (3-4-5 doubled).4. Percentage Swapping
x% of y is always equal to y% of x. Use the one that's easier to calculate.
16% of 50 is the same as 50% of 16 ➔ Result: 85. FOIL Method
First, Outer, Inner, Last. Use this sequence to never miss a term when multiplying binomials.
(x + 3)(x + 2) ➔ x² + 2x + 3x + 6 ➔ x² + 5x + 66. Interior Angle Sum
To find the sum of angles in any n-sided polygon, use the formula: (n - 2) × 180°.
A hexagon (6 sides) ➔ (6 - 2) × 180 ➔ 4 × 180 = 720°7. Squaring Numbers Ending in 5
Multiply the first digit by the next number up, then add '25' at the end.
35² ➔ 3 × 4 = 12 ➔ Result: 12258. Perpendicular Slopes
Perpendicular lines have 'negative reciprocal' slopes. Flip the fraction and change the sign.
If Line A has slope 2/3, Line B (perpendicular) has slope -3/2.9. The Math-to-English Dictionary
'Is' means equals (=), 'of' means multiply (×), and 'per' means divide (/).
'15 is 30 percent of what number?' ➔ 15 = 0.30 × x10. Area vs. Circumference
Area is the space inside (πr²), Circumference is the distance around (2πr).
Circle with radius 4: Area = 16π, Circumference = 8π.