Here's how the Search box works, for those who need it (I had to test it all today for myself, because I was a bit confused):
123 will find everything that contains 123
123
ABC123
123XYZ
ABC123XYZ
ABC 123
123 XYZ
ABC 123 XYZ
ABC123 XYZ
ABC 123XYZ
word:123 and word:"123" will find everything that contains 123, as long as it's isolated from other words
123
ABC123
123XYZ
ABC123XYZ
ABC 123
123 XYZ
ABC 123 XYZ
ABC123 XYZ
ABC 123XYZ
word:" 123" will find everything that contains [SPACE]123 AND is not connected to any other word
123
ABC123
123XYZ
ABC123XYZ
ABC 123
123 XYZ
ABC 123 XYZ
ABC123 XYZ
ABC 123XYZ
word:"123 " will find everything that contains 123[SPACE] AND is not connected to any other word, OR it's the last word in a sentence/string/etc, as long as it's not connected to any previous word.
123
ABC123
123XYZ
ABC123XYZ
ABC 123
123 XYZ
ABC 123 XYZ
ABC123 XYZ
ABC 123XYZ