question_answer 22)

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)

Answer:

(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, \[=\frac{32}{5}\] \[10mm=1cm\Rightarrow 1mm=\frac{1}{10}cm\]\[10mm=1cm\Rightarrow 1mm=1/10cm\]