
MULTIPLICATION BY THREE DIGITNUMBERS :
Ex. 1 : Solve => (1) 321 x 132 = ? (2) 4562 x 345 = ? (3) 69712 x 641 = ?
Soln : (1) 321 x 132 = ?
Step II. 
^{3 2 1} 
^{1 3 2 } 
^{ 7 2} 

as (2x2+3x1 = 7) 
Step III. 
^{3 2 1} 
^{1 3 2 } 
^{ 3 7 2} 

as (2x3+3x2+1x1 = 13, write down 3 and carry over 1) 
Step IV. 
^{3 2 1} 
^{1 3 2 } 
^{ 2 3 7 2} 

as (3x3+1x2+1 = 12, write down 2 and carry over 1) 
Step V. 
^{3 2 1} 
^{1 3 2 } 
^{4 2 3 7 2} 

as (1x3+1 = 4) 
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Mizba
said on : 20160816 04:49:25  didn't understand third step.

Ramandeep
said on : 20150831 14:56:06  Another method of understanding...
3digit multiplication will be done as follows. multiply 325*432
step1: u*u= 2*5 = 10, write 0 at unit place. carry=1
step2: u*t+t*u+1(ie.carry )=20, write 0 at ten place, carry=2
step3: u*h+h*u+t*t+2(carry) =34, write 4 at hundred place, carry=3
step4: t*h+h*t+3(carry) = 20 write, 0 at thousand place, carry=2
step5: h*h+2(Carry ) =14 write 14 at ten thousand place.
ans= 140400
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