You can set up cells that automatically calculate sums, products, and other calculations for a column of numbers or any chosen group of cells.
Numbers also provides more than 250 predefined mathematical functions and formulas for statistics, financial, engineering, and several other applications.
Add the values of specified cells:
Double-tap the cell where you want the result to appear, and then tap 
to open the keyboard for formulas and functions.
To quickly add the values in a column, use the first empty cell at the bottom of the column as the results cell.
Tap SUM in the keyboard.
To adjust the range of cells included in the sum, drag the cell selection handles.
To add values in discontiguous cells or cell ranges, select one cell or a range of cells that you want to use in your calculation. Tap elsewhere in the table or in another table to include values from a discontiguous cell, and then drag the cell selection handles to select a cell range.
When you’re done, tap 
above the keyboard on the right side of the formula bar.
If you tap 
in the formula bar, you’ll exit the current cell without saving the formula into it.
Subtract, multiply, or divide cell values:
You can create simple or complex arithmetic formulas within cells to perform calculations on the values in any cells you specify.
Double-tap the cell where you want the result to appear, and then tap to open the keyboard for formulas and functions.
Tap 
, and then select a cell to use as the first argument in your formula, or type a static value.
Tap an operator on the left side of the keyboard, and then select a cell to use as the next argument in your formula, or type a static value.
Repeat steps 2 through 4 until you’ve completed your formula.
Tap 
, and then tap on the right side of the formula bar.
Preserving row or column addresses in formulas:
If you want to “freeze” a cell address in a formula, so that you can use this same formula elsewhere in your spreadsheet without changing the cell references, do the following:
Double-tap the cell with the formula whose cell addresses you want to maintain.
Tap the triangle on the token representing the cell range you want to preserve.
Slide Preserve Row or Preserve Column to ON for the beginning or end addresses of the selected range. If you change the number of rows or columns in the table, or if you move the formula to a different cell, the preserved row or column references are adjusted, but maintain their absolute original cell references.
If you slide any of the settings to OFF, those row or column references are adjusted to be relative to the cell in which the formula is located if you move the formula to a new location or change the number of rows or columns in the table.
Insert predefined functions into cells:
Double-tap the cell where you want the result to appear, and then tap to open the keyboard for functions.
Tap “functions” in the keyboard, and then tap Categories in the window that opens. You can access all of the available functions in this functions browser.
Tap the name of the category you want, and then tap the name of a function to insert it into the formula bar. Scroll to see the entire list within a category. Tap Recent at the top of the window for quick access to any functions you recently used.
If you’re not sure which function to use, tap 
next to the name of each function to read more details about it.
After you select a function, tap each of the tokens in the formula bar, and then select a cell or cell range to replace the argument name with a cell address or other data, as needed.
If an argument requires a static alphanumeric entry, tap “abc” on the keyboard, type your entry, and then tap Done in the formula bar.
If an argument requires a static date, time, or duration entry, tap 
on the keyboard, enter the time values, and then tap Done in the formula bar.
To toggle a Boolean value (true or false), tap “true/false” on the keyboard.
To add a new Boolean value token, tap “true/false” on the keyboard.
If you selected a cell or cell range, and you want to make the cell address relative so that you can use this same formula elsewhere in your spreadsheet, tap the up arrow on the right side of the cell address token in the formula bar. Then slide Preserve Row or Preserve Column to OFF for the beginning or end addresses of the selected range.
When you’re finished, tap on the right side of the formula bar.
Copy and paste a mathematical formula:
If you want to reuse a similar calculation in multiple locations in your spreadsheet, you can copy and paste functions and formulas from one cell to other cells. Depending on whether you want to copy an entire formula or only a part of a formula, do either of the following:
To copy an entire formula from a cell, do the following:
Tap once to select the cell, and then tap it again.
Tap Copy.
Select the cell where you want to paste the formula, and then tap it again.
Tap Paste.
Tap Paste Formulas.
To copy only part of the formula in a cell, do the following:
Double-tap in the cell that contains the formula or function you want to copy. The keyboard appears.
Double-tap at the end of the formula or function within the formula bar at the top of the keyboard, and then tap Select All.
Drag the blue drag points to encompass only the parts of the formula you want to copy, and tap Select.
Tap Copy.
Double-tap the cell where you want to paste the formula or function. The keyboard appears.
Tap , and then double-tap in the formula bar.
Tap Paste.
Copy and paste only the result of a formula:
You can copy only the result of a formula cell and paste it to another cell.
Tap once to select the cell, and then tap it again.
Tap Copy.
Tap the cell where you want to paste the formula, and then tap it again.
Tap Paste.
Tap Paste Values Only.