Whole Number Computation

This concept is the same as same change for subtraction only you are doing the opposite change. This means if you add four to one number you will subtract four from the other number.

Add the numbers beginning with the left most digits and move to the right.Example 724 + 543Think: 700 + 500 = 1200 20 + 40 = 60 4 +3 = 7Then 1200 + 60 + 7 = 1267

Add the numbers beginning with the left most digits and move to the right.Example 724 + 543Think: 700 + 500 = 1200 20 + 40 = 60 4 +3 = 7Then 1200 + 60 + 7 = 1267

Break up the numbers after the first addend. Add the parts, bridging from one number to the next.Example 742 + 148Think: 742 + 100 = 842 842 + 40 = 882 882 + 8 = 890

Break up the numbers after the first addend. Add the parts, bridging from one number to the next.Example 742 + 148Think: 742 + 100 = 842 842 + 40 = 882 882 + 8 = 890

Create numbers that give you a sum that is easy to use in your head.Example 45 + 57Think: 45 and 55 are considered compatible because they add to 100 which is an easy number to work with, so: 45 + 57 = 45 + (55+2) = 100 + 2 = 102

Create numbers that give you a sum that is easy to use in your head.Example 45 + 57Think: 45 and 55 are considered compatible because they add to 100 which is an easy number to work with, so: 45 + 57 = 45 + (55+2) = 100 + 2 = 102

Reformulate a sum to one that is more readily obtained mentally.Example 23 + 67Think: 23 + 67 -3 +3 20 + 70 = 90

Reformulate a sum to one that is more readily obtained mentally.Example 23 + 67Think: 23 + 67 -3 +3 20 + 70 = 90

Let a and b be any thwo whole numbers. Then the product of a and b, written a x b, is defined by a x b = b+b+b+.........+b, when a is not equale to 0

83 27 ---- 80*20 -> 1600 80* 7 -> 560 3*20 -> 60 3* 7 -> 21 ---- 2241

Write each number at the head of a column.Double the number in the first column, and halve the number in the second column.If the number in the second column is odd, divide it by two and drop the remainder.If the number in the second column is even, cross out that entire row.Keep doubling, halving, and crossing out until the number in the second column is 1.Add up the remaining numbers in the first column. The total is the product of your original numbers.

The Egyptian Method of multiplication is a three-stage process. In the first stage one forms two columns, one for each factor. The entries in both columns are formed by repeated doubling. The first column starts with a 1, and doubling is done until one reaches the largest power of two not exceeding the first factor. The second column starts with the second factor, and repeatedly doubles as often as was done in the first column. In the second stage, working bottom to top, one identifies the subset of entries in the first column that adds up to the first factor, and one crosses out the other entries. In the third stage one adds up the corresponding entries in the second column. The example blow assumes that the addition is done using the fast traditional algorithm with carries done mentally. 83 * 27 + 1 27 + 2 54 4 108 8 216 + 16 432 32 864 + 64 1728 -- ---- 83 2241

Easy and fun!Basically, it is a competition between the children and teacher. The teacher ask quite hard Maths questions. If the children get the answer right, they get one point. If they get it wrong, the teacher gets a point. The first to score 5 points gets a permanent point on a scoreboard.

Let a and b be whole numbers. The difference of a and b, written a - b, is the unique whole number c such that a = b + c

The rule states: "If you add the same number to both numbers in the problem, the answer is the same. Likewise, If you subtract the same number from both numbers in the problem, the answer is the same." Using this rule makes the problem more user friendly by changing the second number in the problem to a number with a zero in the ones place.Example12 - 8 = 4Add 4 to both the 12 and the 8.(12 + 4) - (8 + 4) = 16 - 12 = 412 - 8 = ?Or subtract 6 from both the 12 and the 8. By subtracting 6 from bothnumbers you simplify both number and can subtract without regrouping.(12 - 6) - (8 - 6) = 6 - 2 = 4

Lets play a quick game!The children stand at the back of the class and answer differentiated multiplication questions. They sit down when they have answered a question correctly. The last person standing has to do a forfeit. Forfeits can include being the teacher's slave for the morning, tidying the classroom or anything silly.

Just like doing it by hand, now do it mentally!

If the problem is- 5/330 • Ask “5 times what tens number gives an answerclosest to 330 without going over?” • 5 x 60 = 300 but 5 x 70 = 350, so 60 gives usthe answer closest to 300 without going over. • Draw a second rectangle section to the right ofthe first section. • Write a plus sign after the 60 between the twosections. • Write 30, the difference from the firstsection, inside the second section. • Ask, “5 times what number gives an answerclosest to 30 without going over?” • 5 x 6 = 30 • Write 6 at the top of the second section. • Multiply 5 by 6 to get 30. • Write 30 below the existing 30. • Subtract 30 from 30 to get 0. • Write the difference, 0, below the secondrectangle. • Add the quotients from each section to findthe quotient: 60 + 6 = 66. • So, 330 ÷ 5 = 66.60 + 6 = 66