Education Technology

# Knowledge Base

## Solution 13344: Calculating lcm() (Least Common Multiple) of Two Arguments on the TI-89 Family, TI-92 Family and Voyage™ 200 Graphing Calculators.

### How do I find the least common multiple of two arguments on the TI-89 family, TI-92 family or Voyage 200 graphing calculator?

The lcm() function returns the least common multiple (LCM) of two arguments. The LCM of two fractions is the LCM of their numerators divided by the greatest common divisor (GCD) of their denominators. The LCM of fractional floating-point numbers is their product. For two lists or matrices, lcm() returns the LCMs of the corresponding elements. The proper syntaxes for the lcm() function are as follows:

lcm(number1,number2)   Þ   expression
lcm(list1,list2)   Þ   list
lcm(matrix1,matrix2 Þ   matrix

The lcm() function can be accessed in the MATH/Number menu by following the keystrokes below:

1) While on the Home screen, press [2ND] [MATH] to access the MATH menu.
2) Press [1] or [ENTER] to select the 1:Number submenu
3) Use the directional keys or press [ALPHA] [B] to select to B:lcm(.

lcm() can also be accessed in the CATALOG.

Please Note: On a TI-92 family or Voyage 200 calculator, just press [B] (since there is no [ALPHA] key due to those units' QWERTY keypad.

The following examples demonstrate how to use lcm():

Example:  Find the LCM of 6 and 9.

1) Press [2ND] [MATH] [1], use [↓] to select B:lcm(, then press [ENTER]
2) Press [6] [,] [9] [)] ¾ The entry line should display "lcm(6,9)".
3) Press [ENTER] ¾ The answer of 18 is displayed.

Example:  Find the LCM of the list {1/3, -14, 16} and the list {2/15, 7, 5}.

1) Press [2ND] [MATH] [1], use [↓] to select B:lcm(, then press [ENTER]
2) Press [2ND] [{] [1] [÷] [3] [,] [(-)] [1] [4] [,] [1] [6] [}] [,] [{] [2] [÷] [1] [5] [,] [7] [,] [5] [}] [)] ¾ The entry line should display "lcm({1/3,-14,16},{2/15,7,5})".
3) Press [ENTER] ¾ The answer list of {.044444, 14, 80}.

For additional instructions on using this and other functions, refer to the online guidebooks for the specific calculator model being used.