calculate 888-880+872-864+856-848+...+24-16+8?

Method 1:
888 - 880 + 872 - 864 + 856 - 848 + ... + 24 - 16 + 8
= 8 × (111 - 110 + 109 - 108 + 107 - 106 + ... + 3 - 2 + 1)
= 8 × [(111 + 110 + 109 + 108 + 107 + 106 + ... + 3 + 2 + 1) - 2 × (110 + 108 + 106 + ... + 4 + 2)]
= 8 × [(111 + 110 + 109 + 108 + 107 + 106 + ... + 3 + 2 + 1) - 4 × (55 + 54 + 53 + ... + 2 + 1)]
= 8 × [(112 × 111 ÷ 2) - 4 × (56 × 55 ÷ 2)]
= 4 × [(112 × 111) - 4 × (56 × 55)]
= 4 × (12432 - 4 × 3080)
= 4 × 112
= 448

Method 2:
888 - 880 + 872 - 864 + 856 - 848 + ... + 24 - 16 + 8
= (888 - 880) + (872 - 864) + (856 - 848) + ... + (24 - 16) + 8
= 8 + 8 + 8 + ... + 8 + 8
= 8 × (880 ÷ 16 + 1)
= 8 × 56
= 448

56x8=448

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