1. Use the LEN functon to get the length of the string (25 characters, including spaces).
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2. The SUBSTITUTE function replaces existing text with new text in a string. LEN(SUBSTITUTE(A1,B1,"")) equals 13 (the length of the string without the words dog). If we subtract this number from 25, we get the length of the dog instances (25-13=12).
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3. Dividing this number by the length of the word dog (3), gives us the dog instances (12/3=4).
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