• # question_answer22) Express as cm using decimals. (a) 5 mm (b) 60 mm (c) 164 mm (d) 9 cm 8 mm (e) 93 mm TIPS we know that, $13.7=\frac{137}{10}$ So, to express mm as cm, multiply mm by $=\frac{137}{10}$ (i.e. tenths)

(a) We know that, $21.2=21+\frac{2}{10}=\frac{21\times 10}{1\times 10}+\frac{2}{10}$ $=\frac{210}{10}+\frac{2}{10}=\frac{210+2}{10}=\frac{212}{10}$$=\frac{212\div 2}{10\div 2}=\frac{106}{5}$ (b) We know that, $\because$ $\therefore$$21.2=\frac{212}{10}$ (c) We know that, $=\frac{106}{5}$ $6.4=6+\frac{4}{10}=\frac{6\times 10}{1\times 10}+\frac{4}{10}$$=\frac{60}{10}+\frac{4}{10}=\frac{60+4}{10}=\frac{64}{10}$ (d) We know that, $=\frac{64\div 2}{10\div 2}=\frac{32}{5}$ $\because$$\therefore$ $6.4=\frac{64}{10}$(e) We know that, $=\frac{32}{5}$ $10mm=1cm\Rightarrow 1mm=\frac{1}{10}cm$$10mm=1cm\Rightarrow 1mm=1/10cm$