We have numbers. Fingers.
Then we use ruler or scale.
We measure 7cm.
Our eyes see 1+2+3+4+5+6+7. Though only 7 cm. And We come out with an accurate formula of (n(n+1))/2.
Next step.
We see inches. We don't get confused. We multiply. By 2.54.
Multiply.
And (n(n+1))/2 is multiplied. We come out with accurate formula of ((2n)!) =2(1)2(1+2+3)2(1+2+3+4+5) . . . .2(1+2+3+4+5+....(2n-1))
We come out with accurate formula in both cases. Possibly proudness. An internal thing.
Qayanat calculus is above psychology.
Approximate integral the reverse.