Simple calculation of Grade Five score: 1 / (10 * 12) + 1 / (12 * 14) + 1 / (14 * 16) + 1 / (16 * 18)

Simple calculation of Grade Five score: 1 / (10 * 12) + 1 / (12 * 14) + 1 / (14 * 16) + 1 / (16 * 18)

1/（10*12）=1/2(1/10-1/12)
1/（10*12）+1/（12*14）+1/（14*16）+1/（16*18）
=1/2(1/10-1/12+1/12-1/14+1/14-1/16+1/16-1/18)
=1/2(1/10-1/18)
=1/45

Number reasoning: 12,2,2,3,14,2,7,1,18,3,2,3,40,10_______ ,4

The first number divided by the second number equals the third number multiplied by the fourth number
So fill in 1

Mathematical reasoning problems: 12,2,3,14,2,7,1,18,3,2,3,40,10, () 4

I think this is right: 12,2,3,2,14,2,7,1,18,3,2,3,40,10, () 4
In this case, the value in () is 1,
Because: 12 = 2 × 3 × 2
14=2×7×1
18=3×2×3
40=10×（1）×4
If the original question is correct,