Exercise 1.5 Primes, Powers And Square Roots Worksheet - Heinemann Maths Zone Page 9
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11Summary
• Set out solutions to worded problems by putting headings and writing
calculations in logical sequence.
• Estimate products and quotients by rounding numbers to the leading digit.
• Order of operations requires bracketed calculations to be done first, working
from inner brackets, then multiplication and division as they appear, then
addition and subtraction as they appear.
• Primes are numbers with exactly 2 factors: themselves and 1.
• Index notation is a way of writing repeated factors as a power of the factor.
• Taking a square root is the opposite of squaring a number.
FAQs
What is the largest multiple of 9?
Numbers don’t have ‘largest multiples’. The multiples of 9 continue
forever: 9, 18, 27, 36, …
Is 1 a prime number?
No. A prime number has two factors. 1 is neither composite nor prime.
Skills
1 Use rounding to the first digit to estimate these products.
1.2
(a) 3741 × 22
(b) 265 × 341
(c) 986 × 35
2 Use rounding to the first digit to estimate these quotients.
1.2
(a) 25 736 ÷ 49
(b) 96 001 ÷ 17
(c) 25 000 ÷ 621
3 Use rounding to the first digit to estimate these, and then use a calculator
1.1, 1.2
to work out how far off your estimate was from the exact answer.
(a) 73 − 29 + 5628
(b) 17 × 35 × 241
(c) 28 × 89 − 2455
4 Work these out using your calculator.
1.3
(a) 258 × (231 − 162)
(b) [(832 − 94) ÷ 41] × 112
5 Find, without using a calculator:
1.3
(a) 9 ÷ (2 + 1) − 2
(b) 12 − 6 × 2 + 11
(c) (13 − 5 × 2) + (20 ÷ 10)
(d) [5 × (9 + 1)] − 3
6 Choose the correct answer.
1.3
In the calculation of 2 × [30 ÷ (4 − 1)] + 6 the first operation to do is:
A +
B −
C ×
D ÷
E any of these symbols
7 Choose the correct answer. (5 + 6) × 2 + (15 − 3 × 2) − 6 is equal to:
1.3
A 40
B 20
C 32
D 25
E 28
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