To estimate a number in math, round the last digit of a number up or down to the nearest zero number. This is sometimes referred to as the nearest 10. More » Math Arithmetic

An estimate calculator is a helpful financial planning aid that figures the approximate cost of an item or scenario. Government agencies, such as the IRS and the Social Security Administration, provide estimate calculato... More » Business & Finance Financial Calculations

To estimate postage it is necessary to know the destination of the parcel, the zip code from which the parcel is being sent, the zip code for the destination, whether the package contains live animals, if the package req... More » Business & Finance Mail & Shipping

As a general rule of thumb, numbers should be rounded down if the final digit in a number is from 0 to 4, and rounded up if it's 5 to 9. Rounding sometimes involves more than one digit; some situations may call for round... More »

To tell if a number is evenly divisible by three, add all the digits in it until you arrive at a single digit. For instance, the number 9234 adds up to 18, which adds up to nine. Nine is evenly divisible by three, so 923... More » Math Arithmetic

For each represented digit on a Touch Math number chart, a small number of "touch points," or small dots whose quantity is equal to the numerical value of a given digit, are added. Touch Math charts may include arithmeti... More » Math Arithmetic

The divisibility rule for 7 dictates that a number is divisible by 7 if subtracting 2 times the digit in the one's column from the rest of the number, now excluding the one's column digit, yields a number that is divisib... More »