Edexcel IGCSE Math A 1.3.HA Converting Recurring Decimals to Fractions
Practise using algebraic subtraction to convert recurring decimals into fractions in their simplest form.
Syllabus
First assessment 2018
Course
Math A 4MA1
Level
Higher
Exam points
define x as the recurring decimal and multiply by a suitable power of ten
subtract aligned equations to eliminate the repeating digits
solve for x and simplify the resulting fraction fully
1.3.HA Recurring decimals as fractions question 1
[Maximum number: 2]
Use algebra to show that 4.5˙7˙=43319
E.g. x=4.57…. and 100x=457.57….
or 10x=45.757.... and 1000x=4575.7...
or x=0.57…. and 100x=57.57… or 10x=5.757…. and 1000x=575.7….
M1 for selecting 2 recurring decimals that when subtracted give a whole number or terminating decimal eg 453 or 4530 etc eg 100x=457.57… and x=4.57… or 1000x=4575.7… and 10x=45.757… with intention to subtract. (If recurring dots not shown then allow 10x=45.757, 100x=457.57, and 1000x=4575.7 to at least 5 sf) or 4+0.5757 and eg x=0.57…,100x=57.57… with intention to subtract.
E.g. 100x−x=457.57…−4.57…=453 and 99453=33151 or 43319 or 1000x−10x=4575.7…−45.757…=4530 and 9904530=33151 or 43319
or 100x−x=57.57…−0.57…=57 and 9957 or 3319 (so) 4.5¨7˙=43319
or 1000x−10x=575.7…−5.757…=570 and 990570 or 9957 or 3319 (so) 4.5˙7=43319