Multiply the following with suitable short method =455 by 999 , 401 by 399 , 4001 by 4001 , 1999 by 1999
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Answer:
Step-by-step explanation:
455*999
=(455)(1000-1)
= 455000-455
= 454545
401*399
=(400+1)(400-1)
=400²-1² (a²-b²=(a+b)(a-b))
=40000-1 = 39999
4001*4001
(4000+1)(4000+1) [ (a+b)²=a²+b²+2ab ]
=4000²+8000+1
= 16000000+ 8000+1
= 16008001
1999*1999
= 1999²
=(2000-1)² [ (a-b)²=a²+b²-2ab ]
=2000²+1²-2*2000*1
=4000000+1-4000
=3996001
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