Use only number in a alpha numeric cell & Data Validation

Cell J1 Header

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Cell J2 formula

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shows error #VALUE! how can i retain the numeric character in J1 and keep description VAT without altering its format.

Column L has Data Validation "List" how can i get predictive text options after inputing few characters. for example if the list contains Sundry Debtors, Sundory Expenses, Sundry Creditors, Sales and Sundry is inputed on L2 it should provide me 3 options to select from.