When a number has a lot of digits it is very difficult to do operations with it. Often, we change this number for another one which is more manageable, ending in zeros. This change is called ''rounding'‘.
Example: 2458 is nearer 2500 than 2400.
To round a number to a particular digit (or order of units) we substitute all the digits on the right of this order for zeros and, if the first substituted digit is greater than or equal to 5, we round up the previous digit too.
Exercises:
1.- Round these numbers to the nearest 10:
a) 234 b) 1548 c) 385
2.- Round these numbers to the nearest 100:
a) 844 b) 7654 c) 2540 d) 1972
Solutions:
1.- a) 230: b) 1550; c) 390
2.- a) 800: b) 7700; c) 2000