When you press the Equal (=) Key, if the Solution is equal to your Birthday, K.K. Slider will make a quick appearance with some Flowers on screen. For example, if your Birthday is November 19, the number 1,119 would make K.K. appear after hitting the key. October 10 would be 1,010, June 6 would be 606, etc.
Tom Nook
Tap "Equals" and if the total has digits that are all the same number or are in sequential order, Tom Nook will appear accompanied by a short melody. He will have balloons if the digits were all the same number, or flowers if the digits were in sequential order.