This information is from "The Writer's Handbook" by Allan B. Lefcowitz, 1976. It kind of dances around the issue because it is a college text, and this is an elementary school grammatical error.
"Hyphenate spelled-out numbers from twenty-one through ninety-nine" page 219
"Spell out numbers that come at the beginning of a sentence: One thousand-sixty-nine-pound Robert Earle Hughes was ..." page 209
"Spell out numbers or amounts of less than one hundred. Use figures for larger amounts" page 209
"Fine writing refers to stilted, artificial diction. Often it results from a writer's misconception that effective writing should not sound like speech because it is a different "language" from speaking. However, effective writing is not another language; it is natural, idiomatic English used appropriately in context" page 187
And finally from me, 'and' is a coordinating conjunction that those teachers should have learned the proper use of long ago. They should consult an elementary school text before sticking their noses in the air and acting all formal.