How to survive WITHOUT your calculator! Mental Math How to survive WITHOUT your calculator!
Fractions Converting decimals (#’s < 1) to fractions: Make decimal a fraction Multiply by numerator Divide by denominator Set 1: 0.1 x 0.2 When multiplying 2 fractions: Multiply the numerators Multiply the denominators Simplify Set 2: 0.1 x 0.6
Scientific Notation WITHOUT a Calculator
Adding and Subtracting Step 1: Adjust the powers of 10 in the 2 numbers so that they are the same. (Tip: It is easier to adjust the smaller power to equal the larger power). (Tip: One will not be in true scientific notation) Step 2 : Add or subtract the numbers. Step 3 : Give the answer in scientific notation.
2.0 x 102 + 3.0 x 103 = .20 x 103 + 3.0 x 103 .2 x 103 + 3.0 x 103 = (.2+3) x 103 = 3.2 x 103 Step 1: Adjust the powers of 10 in the 2 numbers so that they are the same. (Tip: It is easier to adjust the smaller power to equal the larger power). (Tip: One will not be in true scientific notation) Step 2 : Add or subtract the numbers. Step 3 : Give the answer in scientific notation. 2.0 x 107 - 6.3 x 105 2.0 x 107 -.063 x 107 = (2.0-.063) x 107 = 1.937 x 107 1. Make exponents the same 2. Subtract 2.0 - .063 and keep the 107
Multiplying To multiply numbers in scientific notation: Step 1 : Group the numbers together. Step 2 : Multiply the numbers. Step 3 : Add the powers of 10. Step 4 : Give the answer in scientific notation.
3x108 x 1.5x1023 = (3x1.5)x(108+23) Step 1 : Group the numbers together. Step 2 : Multiply the numbers. Step 3 : Add the powers of 10. Step 4 : Give the answer in scientific notation. =4.5x1031 4.0x108 x 5.0x106 = (4.0x5.0) x 108+6 = 20x1014 =2.0x1015
Dividing To divide numbers in scientific notation: Step 1 : Group the numbers together. Step 2 : Divide the numbers. Step 3 : Subtract the powers of 10. Step 4 : Give the answer in scientific notation.
4.5x108 3x105 4.5 3 x 108-5 Step 1 : Group the numbers together. Step 2 : Divide the numbers. Step 3 : Subtract the powers of 10. Step 4 : Give the answer in scientific notation. = 1.5x103
Scientific Notation Summary Adding and subtracting Make the exponents the same Multiplying and dividing Add or subtract the exponents