# Mathematics (Primary Classes)

## WEIGHT

The units used for measuring weight are kilogram (kg) and gram (g). 1000 gram = 1kg 1000kg = 1 ton   EXAMPLE1 Change to kilogram 2000g to kilogram   1000g = 1kg 2000g = m Cross multiply 1000 Ã— m = 2000 x 1 1000m = 2000 m = 2000 = 2kg Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  1000   […]

## VOLUME OF CYLINDER

Volume of cylinder = Ï€r2h = Ï€ x r x r x h   EXAMPLE Find the volume of a cylinder of radius 3 Â½ cm and height 12cm Solution Â Volume = Ï€ x r x r x h =22Â  x 7 x 7 x 12cm 7Â Â  xÂ  2Â  xÂ  2Â  xÂ  1 = 22

## AREA OF RIGHT ANGLED TRIANGLE

A right-angled triangle has 3 â€“ sides Example 1 Calculate the area of a triangle of height 12cm and base 13cm Solution Area of triangle = Â½ x base x height = Â½ x 12cmÂ  x 13cm 1Â Â Â Â Â Â Â Â Â Â Â  1 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  = 1 x 6cm x 13cm =Â  78cm2   EXERCISE Calculate the area of the

## PROFIT AND LOSS PERCENT

Profit or loss percent is expressed as a percentage of the cost price EXAMPLE 1 An article bought for \$3,000 was sold for \$3,300. Find the profit percent Solution Cost price = \$3,000 Selling price = \$3,300 Profit = \$3300 – \$3,000 = \$300   Profit % = ProfitÂ Â Â Â  x 100 Cost priceÂ Â Â  1

## SIMPLE INTERREST

Meaning of interest: interest means the extra money that you [ay back when ypu borrow money that you receive when you invest money. EXAMPLE 1 find the simple interest on \$1,000 for 5 years at 3% per annum. SOLUTION Principal = \$1,000 (the amount borrowed Time = 5 years (the period for which the money

## MONEY: PROFIT AND LOSS

MEANING OF PROFIT When the selling price of an article is higher or greater than the cost price, we have a profit or gain. Profit = selling price â€“ cost price Â  MEANING OF LOSS When the selling price is less than cost price we have a loss. Loss = cost price â€“ selling price

## SIMPLE PROBLEMS ON PERCENTAGES

Percentages are fractions with 100 as denominator EXAMPLE 1 Change the following fractions to percentages 2/5 =Â  2/5 of 100 = 2/5Â  Ã—Â  100 = 200Â  = 40% 5 EXAMPLE 2 Change these percentage to fractions 75% = 75 Â = 15 = 3 Â Â Â  100Â Â Â Â  20Â Â Â  4 EXAMPLE 3 Change 7 Â½% to fractions in

## RATIO AND PERCENTAGE

Meaning of Ratio The relation between two quantities (both of the same units) obtained by dividing one quantity with another is called ratio. Ratio can be denoted by using the symbol ( : ). EXAMPLE 1Â  What is the ratio between the weight two bags of sugar of 4kg and 6kg respectively? Solution Ratio of

## PROFIT AND LOSS

Example 1 A man bought a leather bag for N350.00 and sold it for N360.00 will he have more money or less money with him? Solution Selling price = N460.oo Cost price =Â Â  – N350.00 Profit (gain) = Â Â N110.00 Â  Note: profit or gain = selling price â€“ cost price   Example 2 If a

## PROBLEM ON MULTIPLICATION OF MONEY

EXAMPLE Find the cost of 3 books at N91.55 each. Solution N91. 55 Ã—Â Â Â Â Â Â Â Â  3 N274.65   EXERCISE 52 x 4 75 x 6 75 x 6 91 x 8 37 x 6 A bag of salt costs N585.40. how much will I pay for 5 bags? What is the cost of 6 meters of

## Money

Addition of Money Example: find the sum of N4.36, N3.79 and N4.82 NÂ Â  K 4Â  Â  36 +Â  3. 7 9 +Â  4. 8 2 Â  Â 12. 9 7 EXERCISES Add up 00, N24.70 and N32.55 20, N174.30 and N132.30 00, N152.10 and N184.20 80, N378.35 and N29.46 Fin the sum, of N168.00 and N276.00

## ESTIMATION

Rounding off decimals to the nearest whole number Rules for rounding off decimals to the nearest whole number When the rounding off decimals to the nearest whole number, look at the digit in the tenths place. If this digit is 5 or greater than 5, replace the digits after the decimal point by zero and

## HIGHEST COMMON FACTOR (HCF)

The product of 2 and 3 is; 2 x 3 = 6 2 and 3 are factors of 6 The factors of a number are numbers that divide the number without a remainder   EXAMPLE Find the common factors of 24 and 36 24 =Â Â  Â 1 x 24 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 36 = Â Â 1 x 36 =Â Â Â

## LEAST COMMON MULTIPLES (LCM)

Example 1: Find the least common multiples of 2 and 3 The multiples of 2 are: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 The multiples of 3 are: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, and 36 Thus the common multiples of 2 and three

## SQUARES AND SQUARE ROOTS OF NUMBERS

SQUARES AND SQUARE ROOTS OF NUMBERS (1- digit and 2 â€“ digit numbers)   Example: 1: find 22 = 4 2 =( 2 x 2) + ( 4 x 4) = 4 + 16 = 20 Example 2: find 42 – 22 = (4×4) â€“ (2 x 2) = 16 â€“ 4 = 12 Example

## MULTIPLICATION OF NUMBERS

MULTIPLICATION OF NUMBERS BY 2-DIGIT NUMBERS Example 1 multiply 25 by 12 Method 1: column form Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  method 2: Expanded form 2Â Â Â  5Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  25 x 12 = 25 x (10 = 2) xÂ  1Â Â Â  2 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  Â Â = (25 x 10) = (25 x 2) 2Â Â  5Â Â  0Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  Â  (25 x 10)Â  Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â Â Â Â Â Â = 250 +