The greatest common factor (GCF) is the largest number that divides evenly into the given numbers. The least common multiple (LCM) is the smallest number that is a multiple of the given numbers.
The distributive property
of multiplication over addition allows us to “distribute” a factor to two different addends (or in more math terms, “over” two different addends). For example, 6(7 + 2) = (6)(7) + (6)(2) = 42 + 12 = 54.
To add or subtract fractions, we need the least common denominator. To find this we find the LCM of the denominators. When we add mixed numbers we add the whole number portion and then add the fractions. If the fractions are improper fractions, we need to change them to a mixed number and again add the whole numbers. The same goes for subtraction.
Finding the sum of decimal numbers can be accomplished by writing the decimal numbers one under the other and keeping the decimal points in a line vertically. Using this method, the whole numbers will be added to whole numbers, tenths added to tenths, hundredths to hundredths, and so on. The decimal point in the sum (the answer) is in the same line with the decimal points in the numbers that were added. Use the same method to find the difference of decimals.
Practice
1) List three multiples of nine.
2) List the factors of 64.
3) List three multiples of 4.
4) List factors of 42.
5) List five prime numbers.
6) List five composite numbers.
7) What is the prime factorization of 35?
8) What is the prime factorization of 16?
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