## Step 1

Write addresses the same as you would for an envelope, with the street address on one line and the city, state and ZIP code on the next line. Example: 123 Elm Street on one line and Eagletown, LA 71234 on the next.

## Step 2

Write contact phone numbers as either (999) 123-4567 or 999-123-4567.

## Step 3

Write out the month in dates, such as January 1, 2012.

## Step 4

Stick to words for zero through one hundred and numerals for 101 and above. You could say your organization has eighty-five members or 185 members.

## Step 5

Use numerals for consistency, if your letter includes numbers above and below 100. This avoids awkward phrasing, such as "between ninety-five and 105."

## Step 6

Spell out large, round numbers with only a numeral at the beginning, as in 8 million. Use numerals for figures that would require many words, opting for 775,000 rather than seven hundred seventy-five thousand.

## Step 7

Use numerals for all percentages, as in 87 percent or 87.75 percent. You can use either the word percent or the sign % as long as you remain uniform. Do not include trailing zeroes (such as 55.0 percent) unless directing your letter to a math or science audience warranting significant digits. Even tens numbers can be in words, as in twenty percent, though keeping consistent with other percentages would trump this.

## Step 8

Use numerals for decimal figures such as 3.14, and include a zero at the beginning of a number less than one, such as 0.375. Again, omit trailing zeroes unless they are central to the accuracy of the data that you're discussing.

## Step 9

Write out fractions in words, such as two-fifths, only if the number is less than one. Use numerals for greater mixed numbers, such as 3 3/4.

## Step 10

Use the dollar sign and numerals for money amounts below 1 million, omitting the decimal and zeroes for whole dollars, such as $15 or $20,000.

## Step 11

Write round figures of 1 million or more with only the beginning numerals, as in $10 million. You can use a maximum of two decimals for a number like $12.75 million, but otherwise use only numerals, such as $12,755,500.