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Test 24-May-17 Level F – Fri 12th Dec Revise Chapter 13 - Decimals Chapter 7 – Scientific Notation Chapter 37 – Drawing Skills Chapter 47 – Time / Distance / Speed Decimals 24-May-17 Revision Learning Intention 1. To revise Level F work. Success Criteria 1. Add and subtract decimals 2. To multiply and divide decimal numbers 3. To round to any number of decimal places 4. To round to any number of significant figures Decimals 24-May-17 Revision Level E 1. What does 6 stand for in 0.26 ? 6 hundredths 2. Name one number which lies between 0.1 and 0.2 ? 0.11 3. Round to 1 decimal place 34.055 34.1 4. Calculate 4.76 x 100 Shop A 80p Shop B 79p 476 5. Calculate 567.89 ÷ 1000 0.56789 B is cheaper! 6. Shop A sell 25 CD’s for £20 and Shop B sells 40 CD’s for £31.40. Which shop is the cheapest. Decimals 24-May-17 Addition & Subtraction Example : 3.2 + 0.487 + 5.73 3.200 0.487 5.730 9.417 1 11 Keep point in line Decimals 24-May-17 Addition & Subtraction Example : 6.2 – 3.19 + 1.783 6.200 +1.783 7.983 3.190 4.793 Add first Then subtract Decimals 24-May-17 Simple Multiplication Example 1 : 0.6 x 0.4 6 x 4 = 24 0. 24 2 digits after decimal place Example 2 : 0.09 x 0.3 9 x 3 = 27 0. 027 3 digits after decimal place Decimals 24-May-17 Simple Multiplication Example 3 : 0.071 x 0.5 71 x 5 = 355 4 digits after decimal place 0. 0355 Decimals 24-May-17 Division of a Decimal Do not attempt to divide by a decimal, multiply the divisor so it is a whole number first. Example 1 : 3.5 ÷ 0.7 35 ÷ 7 = 5 x 10 x 10 Example 2 : 0.8 ÷ 0.2 8÷2= 4 Decimals 24-May-17 Division of a Decimal Do not attempt to divide by a decimal, multiply the divisor so it is a whole number first. Example 3 : 0.036 ÷ 0.04 3.6 ÷ 4 = 0.9 x 100 Example 4 : 24 ÷ 3000 24 ÷ 3÷1000 = 0.008 Decimals 24-May-17 Rounding to Any Number of Decimal Places When rounding to : 1 decimal place look at 2nd decimal figure e.g. 2.46 2 decimal place look at 3rd decimal figure e.g. 6.456 3 decimal place look at 4th decimal figure e.g. 3.7846 4 decimal place look at 5th decimal figure e.g. 13.1146 Decimals 24-May-17 Rounding to Any Number of Decimal Places Example : The number 4.2615937 Rounded to 1 decimal place, the number is 4.3 Rounded to 2 decimal place, the number is 4.26 Rounded to 3 decimal place, the number is 4.262 Rounded to 4 decimal place, the number is 4.2616 Significant Numbers 24-May-17 In mathematics a figure or digit is significant if it gives an idea of both: (i) Quantity (ii) Accuracy IMPORTANT : If zero’s are employed just to position the decimal point then they are considered NOT significant. e.g. 506 cm Has 3 significant figures. 50.6 cm Has 3 significant figures. 0.506 cm Has 3 significant figures. 0.00506 cm Has 3 significant figures. Significant Numbers 24-May-17 IMPORTANT : When dealing with WHOLE NUMBERS you need More information before you can tell if trailing zero’s are significant. Question ? How many significant figures is this number to. 360 Is it 2 or 3 !!! 3 If I said 359 to the nearest ten is 360. How many significant figures. 2 If I said there are 360 deg. in a circle. How many significant figures. YOU NEED TO KNOW THE CONTEXT OF THE QUESTION WHEN DEALING WITH WHOLE NUMBERS WITH TRAILING ZEROS. WORK OUT WHAT THE ZERO MEANS Significant Figures 24-May-17 Decimals 0.001090 To the left of The number Middle of the number To the right of the number Always Significant Not Significant Always Significant Whole Numbers 03060 To the left of The number Middle of the number ? Depends More Info. Not Significant Always Significant Read Question