800m 35cm
154m 49cm
-----------------subtract
we cant subtract 49 cm from 35 cm...so we will borrow a meter....1m = 100 cm......so when borrowing, ur problem becomes :
799m 135cm
154m 49cm
-------------------subtract
645m 86cm
1m = 100cm.....so 645m = (645 * 100) = 64500 cm....plus the 86 cm...
64500 + 86 = 64586 cm <==
or
1 cm = 0.01 meters....so 86cm = (86 * 0.01) = 0.86m plus the 645 meters
645 + 0.86 = 645.86 m <==