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 rods wide along the south side of his farm. How much does he receive at $150 per acre?”

He triumphed in this transaction, began the struggle with the square root of 576. Square roots agonized him. She washed the slate clean with her little sponge. He was leaning close in his effort to comprehend the fiendish little figures that marched so tractably under Selina’s masterly pencil.

She took it up, glibly. “The remainder must contain twice the product of the tens by the units plus the square of the units.” He blinked. Utterly bewildered. “And,” went on Selina, blithely, “twice the tens, times the units, plus the square of the units, is the same as the sum of twice the tens, and the units, times the units. Therefore”—with a flourish—“add 4 units to the 40 and multiply the result by 4. Therefore”—in final triumph—“the square root of 576 is 24.”

She was breathing rather fast. The fire in the kitchen stove snapped and cracked. “Now, then, suppose you do that for me. We'll wipe it out. There! What must the remainder contain?”

He took it up, slowly, haltingly. The house was terribly still except for the man’s voice. “The remainder twice product tens  units” A something in his voice—a note—a timbre. She felt herself swaying queerly, as though the whole house were gently rocking. Little delicious agonizing shivers chased each other, hot and cold, up her arms, down her legs, over her spine.