Practise the method.Example 1In 8454=8×103+4×102+5×10+k, find k.Show worked answerAnswer: 4The ones digit is 4; the remaining place-value contribution is 4.Example 2Calculate 7×103+6×102.Show worked answerAnswer: 7600103=1000 and 102=100. Add the two place-value contributions.Example 3How many times larger is 3×106 than 3×105?Show worked answerAnswer: 10Moving one place left multiplies the place value by 10. The same coefficient cancels in the ratio.