APPROXIMATION OF NUMBERS ROUNDING OFF TO DECIMAL PLACES Archives

APPROXIMATION OF NUMBERS ROUNDING OFF TO DECIMAL PLACES Digits 1,2,34 are rounded down to Zero, while digits 5, 6, 7, 8, and 9 are rounded up to 1 e.g. 126130 to 2 digits A significant figure begins from the first non-zero digit at the left of a number. Digit should be written with their correct place values. Worked example Round off the following to the nearest Thousand (ii) hundred (ii) ten (a) 8615 (b) 16,560 Solution a. i) 8615 ≈ 9000 {to the nearest thousand} ii) 8615 ≈8600 {to the nearest hundred} iii) 8615 ≈8620 {to the nearest ten} b. (i) 16560≈17000 {to the nearest thousand} (ii) 1660≈16, 600 {to the nearest hundred} (iii) 16560 ≈16560 {to the nearest ten} Round off the following to the nearest (i) whole number (ii) tenth (iii) hundred (a) 3.125 (b) 0.493 Solution a. (I) 3.125≈3 {to the nearest whole number} (ii) 3.125≈3.1{to the nearest tenth} (iii) 3.125≈3.13{to the nearest hundredth} b. (i) 3.125≈3 {to the nearest whole number} (ii) 3.125≈3.1{to the nearest tenth} (iii) 3.125≈3.13{to the nearest hundredth Evaluation Round off the following to a) p. (b) 2 d.p. (c) 3 d.p. (1) 12.9348 (2) 5.0725 (3) 0.9002 Square Roots of Numbers The symbol ‘√’ means “square root of”. To find the square root of a number, first find its factors. Examples Find the square root of 11025 Solution (a) √11025 3 11025 3 3675 5 1225 5 245 7 49 7 7 √11025 √(32 x 52 x 72) 3 X 5 X 7105 Example Find the square roots of √54/9 Solution: √54/9 √49/9√49/√97/32 1/3 WEEKEND ASSIGNMENT What is 0.003867 to 3 significant figure (a)0.004 (b)0.00386 (c)0.00387 (d)386 The square root of 121/2 is ____(a)1 3/4 (b)3 1/2 (c)3 3/4 (d)6 1/4 9852 to 3 S.F. is _____(a)990 (b) 9850 (c) 9580 (d) 986 7.0354 to 2 d.p is _____(a) 7.03(b) 7.04 (c) 7.40 (d)7.13 59094 to the nearest hundred is ____(a) 59100(b)59104 (c) 60094 (d) 60194 THEORY Find the square root of 1296 a. What is 0.046783 to 3 significant figure 45.34672 to 2 d.p. is ______ See also SIMPLE INTEREST FRACTIONS H.C.F & L.C.M AND PERFECT SQUARES WHOLE NUMBERS AND DECIMAL NUMBERS BASIC OPERATION OF INTEGERS