It turns out you already had the years in the reference dates row 4.
Try this in A5:N5 and fill down as far as needed. It returns the School names and MULT. Copy and paste into the other tabs or instead group the tabs and enter all at once from tab 'Dec 18-24'.
If you are not familiar with grouped tabs ... click on the first date range tab and while holding down the Shift key click on the last tab. They will be grouped. Enter the formula as above and each sheet will have it's own copy automatically.
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