130
630
To round 1236 to the nearest 100, you need to look at the tens and ones digits. In this case, the tens digit is 3 and the ones digit is 6. Since the tens digit is less than 5, you round down. Therefore, 1236 rounded to the nearest 100 is 1200.
660
2400
660
'94' rounded to the nearest tens is '90'.
130
135
Yes.
1640
94
The ten 1n 2381 is the '8' representing eighty. To round to the nearest ten you need to look at the units; if they are between 0 and 4 the ten stays the same, if they're between 5 and 9 the tens go up to the next number. 74 rounded to the nearest ten would be 70, because the units are between 0 and 4. 76 rounded to the nearest ten would be 80, because 6 is between 5 and 9. 2381 rounds to 2380, because the 1 is between 0 and 4.
60
20
630
Look at the digit in ones place. If it is five or greater, round the digit in tens place to the next higher digit. If the digit in ones place is less than five, leave the digit in tens place as it is. 512162 rounded to the nearest tens is 512160.