Since 9 = 10−1, to multiply a number by nine, multiply it by 10 and then subtract the original number from the result. For example, 9×27 = 270−27 = 243. Online Times Tables Trainer - perfect for kids to learn and practice their times tables independently; and a detailed results record is generated to help them and parents and teachers see exactly how they are getting on. Grid Multiplication Worksheets Grid Multiplication TUxU Partitioned, Grid Multiplication TUxTU Partitioned, Grid Multiplication TUxU, Grid Multiplication TUxTU, Grid Multiplication HTUxTU, Grid Multiplication HTUxHTU

To easily multiply any 2-digit numbers together a simple algorithm is as follows (where a is the tens digit of the first number, b is the ones digit of the first number, c is the tens digit of the second number and d is the ones digit of the second number):is close to 500, which is easy to multiply by. Add and subtract 8 (the difference between 500 and 492) to get

so the final digit is 4, with a 1 carried and added to the 2×6 =12 to give 13, so the next digit is 3 with a 1 carried and added to the 2×1=2 to give 3. Thus, the product is 334. n 2 = n 2 {\displaystyle n a ⋅ d + b ⋅ c ) {\displaystyle (a\cdot d+b\cdot c)} is the addition of the product of the outer digits and the inner digits; OI. b L + b R ) + t L t R {\displaystyle \,10(b_{L}+b_{R})+t_{L}t_{R}} = 10 [ ( x − 5 ) + ( y − 5 ) ] + ( 10 − x ) ( 10 − y ) {\displaystyle \,=10[(x-5)+(y-5)]+(10-x)(10-y)} = 10 ( x + y − 10 ) + ( 100 − 10 x − 10 y + x y ) {\displaystyle \,=10(x+y-10)+(100-10x-10y+xy)} = [ 10 ( x + y ) − 100 ] + [ 100 − 10 ( x + y ) + x y ] {\displaystyle \,=[10(x+y)-100]+[100-10(x+y)+xy]} = [ 10 ( x + y ) − 10 ( x + y ) ] + [ 100 − 100 ] + x y {\displaystyle \,=[10(x+y)-10(x+y)]+[100-100]+xy} = x y {\displaystyle \,=xy} When the digits of b are all smaller than the corresponding digits of a, the calculation can be done digit by digit. For example, evaluate 872−41 simply by subtracting 1 from 2 in the units place, and 4 from 7 in the tens place: 831.This method can be used to subtract numbers left to right, and if all that is required is to read the result aloud, it requires little of the user's memory even to subtract numbers of arbitrary size. will always equal 7, 4x5 will always equal 20, and so some rote learning (learning by repetition and/or memorisation - in this case with worksheets) is a suitable and efficient way to practise and develop mathematical skills and techniques so that they become second nature; hard-wired number facts in a young person’s brain. You don’t have to think when asked what is 2+2: you just know that it is 4. The sooner that a child just knows certain number facts, the better, but that knowledge comes only through practice.