_Lightning calculation_. A's keenest intellectual interest is probably in numbers, and he has responded very readily to his father's instruction in short-cut methods of calculation. By March, 1922, he could very quickly square any number up to 100; multiply any two numbers of a sum not to exceed 200; square any number up to 1000 ending in 5 such as 865, 935, etc.); square any number up to 10,000, ending in 55 or in 555; solve problems in proportion, such as 9 : 21 :: 21 : _x_, 8 ÷ 42 :: _x_ ÷ 21, 8 : 9 :: 10 : _x_, subtract the square of one number ending in 5 from the square of another number ending in 5, where the difference between the two numbers is 10, or 20, or 30 (e.g., 2255² or 2245² or 3345² or 3325²). Also at that age he could calculate series of operations, thus: "Take 2, square it, square that, divide by 4, cube it, add 17, take the square root, add 7, square it, square it, give the result," his calculations taking about five seconds each. EDITOR'S SUPPLEMENT The author's original write-up of Child A ends with the above, written early in 1923. From records in the author's files the following further data concerning later development may be added: _December 26, 1923_ AGE: 9 years 6 months SCHOOL GRADE: Sixth TEST RECORD: Given Stanford-Binet by L. S. H. with Mental Age of 16-11. This would give IQ 178, but the comment is made, "Can no longer be measured by Stanford-Binet." On this day also given Army Alpha, with a score of 128 points, this being the score assigned to chronological age 17 years 8 months. PHYSICAL MEASUREMENTS: Standing height 54.2 inches Sitting height 27.9 inches Weight 74.3 pounds Head circumference 21.5 inches Right grip 14, 17, 18 Left grip 14, 12, 14 TEACHERS' REPORTS. (Private school, September 22-December 19, 1924) "A's reports show that he has attained high credit in mathematics and history; low credit in French, shopwork, art, music, and physical training; average credit in other subjects. His written work shows improvement. "He presents the usual problem of the unadjusted. There is now more alertness in his manner, but still a lack of the will to do work because it is a group demand. Something more of maturity has come to him with his greater freedom. He has started the manual-training problem with some sense of self-discipline. "If he will now attack his work with the mental grip of which he must be capable, and give to the group the benefit of his ability, it will be a joy to have him among us." _December 22, 1924_ AGE: 10 years 6 months SCHOOL GRADE: Seventh TEST RECORD: On Stanford-Binet, passed 4 of the 6 Superior Adult Tests, failing on Tests 1 and 4. Alpha score, 166 points.