1-1/(22*21)-1/(21*22)-1/(22*23)-.-1/(99*100)간편한 계산 -5*(+7과 1/3)+7*(-7또 1/3)+12*(-7 -5*(+7 또 1/3) +7*(-7 또 1/3) +12*(-7 또 1/3) 간편계산

1-1/(22*21)-1/(21*22)-1/(22*23)-.-1/(99*100)간편한 계산 -5*(+7과 1/3)+7*(-7또 1/3)+12*(-7 -5*(+7 또 1/3) +7*(-7 또 1/3) +12*(-7 또 1/3) 간편계산

1, (1-1/2-1/4) ₩ 1/4
=(4/4-2/4-1/4)×4
=1/4×4
=1
2,3/10×(5/7~10/21)
=3/10×(15/21~10/21)-통점
=3/10×5/21
=1/14
3,6 ↓ 20% - 9
=6 ᄋ0.2-9
=30-9
=21