Anyone know why it gives me error or how solve this?

Question

in practice I want to SUM only when B3 is equal to B4 if B3 is less than B4, B4 remains the same but if B3 becomes bigger than B4, B4 WILL BE EQUAL TO B3.

Also I don't want to make sure that if I add a negative number like -10 $ B4 it goes down in value.

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Answer 1

There is a circular reference in your formula. Formulas in google sheets can calculate only with values actually on the sheet.

In figure below:
The B4 cell contains the formula: =MAX(D13:D29);.
And the area D13:D29 is filled by formula: =SUM($B$13:B13).

Values from question: